Defrosting refrigeration apparatus



June 22, 1954 Filed July 27, 1951 G. S. M CLCY DEFROSTING REFRIGERATION APPARATUS 5 Sheets-Sheet @YVITIfJFSSESi 9 -w- MML INVENTOR GRAHAM. s. mcLpY BY 2 M ATTORNEY 3 Sheets-Sheet 2 G. S. M CLOY DEFROSTING REFRIGERATION APPARATUS E sa+- R Y T E N M EM O V. N u M A FIG. 5.

June 22, 1954 Filed July 27, 1951 jlTNgssaa \mu. M L

June 22, 1954 5, MccLQY DEFROSTING REFRIGERATION APPARATUS 3 Sheets-Sheet 3 Filed July 27, 1951 INVENTOR GRAHAM S. MQGLOY WITNESSES ATTORNEY Patented June 22, 1954 DEFROSTING REFRIGERATION APPARATUS Graham S. McCloy, Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 27, 1951, Serial No. 238,935

6 Claims. 1

This invention relates to refrigerating apparatus and more particularly to means for effectively defrosting such apparatus.

In some refrigerating systems on the market today the evaporator of the system is defrosted by circulating warm refrigerant through the system while maintaining the suction pressure in the system high enough to prevent evaporation of the refrigerant flowing through the evaporator. Since the evaporator is usually positioned adjacent portions of the cabinet structure, these portions are cooled to below 32 F. by the evaporator during the refrigerating operation and hence collect frost. During a defrosting operation,these frost collecting portions of the cabinet structure may not be warmed sufficiently to melt the frost collected thereon. The result is an objectionable progressive build-up of the frost which must be removed by hand.

i It is accordingly an object of my invention to 4 effectively defrost portions of the refrigerator cabinet structure which, because of their proximity to the evaporator, collect frost during the refrigerating operation.

Another object of my invention is to accom- In certain present day refrigerators, a cooling unit is provided as a portion of the cabinet structure; which cooling unit serves as a sharp freez ing chamber for the storage of ice and frozen foods. The cooling unit in this type of refrigerator is generally a boxlike structure having refrigerant passages formed in one or more walls thereof. While all portions of the cooling unit will be cooled below 32 F. during the refrigerating operation of the system, and consequently collect frost, those portions of the cooling, unit which do not carry refrigerant will not be warmed sufficiently during the defrosting operation to melt the frost which may have collected thereon. It is accordingly another object of my invention to effectively defrost all portions of a refrigerator cooling unit.

M It is a further object of myinvention to provide anovel cooling unit for mechanical refrigerators which may be quickly and effectively defrosted.

Another portion of the refrigerator cabinet structure which might fall into the above classification is the drip pan and its associated drain which isgenerally positioned beneath the evaporatoror cooling unit to carry away defrost water during the defrosting operation. Occasionally been completely defrosted. During the subsequent refrigerating operation, the drip pan, because of its proximity to the evaporator, will be cooled sufficiently to maintain this ice in a hardened condition as well as to freeze any defrost water which may have remained in the drip pan. This ice build-up sometimes progresses to the point where the drain becomes completely clogged and water overflows from the drip pan during the next defrosting operation.

It is accordingly another object of my invention to raise the temperature of the evaporator drip pan above freezing during the period when the evaporator or cooling unit of the refrigerator is being defrosted.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a vertical sectional view of a refrigerator embodying this invention;

Fig. 2 is a front elevation of the novel cooling unit employed in this invention;

Fig. 3 is an exploded View of the cooling unit shown in Fig. 2;

Fig. 4 is a sectional view of the storage vessel employed in this invention; and

Fig. 5 is a partial vertical sectional view of a refrigerator embodying a modification of this invention.

Referring to the drawings for a description of the invention, the reference numeral l0 designates generally a refrigerator cabinet structure having a food storage chamber I2 in the upper portion thereof and a machine compartment l4 below the food storage chamber. The food storage chamber [2 is surrounded by thermal insulation l5 and has an access opening [6 in the front thereof closed by the door H. A sealed casing H3 in the machine compartment M contains a compressor 26 and an electric motor 22 for driving the compressor. An inlet port 24 of the compressor 26 communicates with the interior of the sealed casing I8. A pressure conduit 26 conducts the refrigerant vapor compressed by the compressor 20 to an air cooled condenser 28 wherein it is cooled and condensed. A liquid line 30 including a capillary tube 32 conducts the refrigerant liquid formed in the condenser 28 to a storage vessel 34 located in 3 the upper portion of the food storage chamber l2, and forming a part of the rapid defrosting apparatus of the refrigerator.

Conduit means 35 are provided for conducting refrigerant liquid and vapor from the storage vessel 35 to the cooling unit 38. As best shown in Fig. 4, the conduit means 35 communicates through one end 39 thereof with a lower portion of the storage vessel 34 and extends upwardly through the top of the vessel 34 and has an elevated portion 68 positioned above the refrigerant liquid within the vessel 34. The conduit means 35 then extends downwardly through the storage vessel 3 and to the cooling unit 38. Restrictor means including an orifice 82 in the conduit means as provides communication between an upper portion of the storage vessel E 3 and that portion of the conduit means 35 extending downwardly through the storage vessel 35. conduit means 36 also has, in accordance with this invention, a heat exchanging portion it be tween the elevated portion 45 and the orifice 42. This heat exchanging portion is arranged in heat transfer relationship with portions of the cooling unit 38, the purpose of which will hereinafter be described.

The cooling unit 38 consists of a generally box like structure having a top wall it, back wall 23, side walls 50, and a bottom wall 52. The cooling unit 33 is suspended within the upper portion of the food storage chamber l2 by suitable means such as brackets 54. The cooling unit 38 defines a sharp freezing chamber 56 having an access opening 5! in the front thereof which is closed by a movable door 58 pivoted at 55 for swinging movement downwardly.

Referring'to Fig. 3, a generally U-shaped sheet metal evaporator 52 having refrigerant passages 64 formed therein formsthe side walls 55 and bottom wall 52 of the cooling unit'38. The cooling unit 33 has a shelf 85 mounted therein which is provided with refrigerant passages 38 and is adapted to support ice trays ts or the like within the sharp freezing chamber 56. The refrigerant passages 64 of the evaporator 62 and the re-- frigerant passages 68 of the shelf 65 are connected in series by means of a conduit it.

The top wall ifi and the back wall 58 of the cooling unit 38 are formed of a generally L-shapeol metal sheet l2 to which the serpentine heat exchanging portion 46 of the conduit secured.

A suction conduit M conducts the vaporized refrigerant from the evaporator 62 downwardly to the motor compressor casing it. The suction conduit 1 has a portion it thereof in heattransfer relationship with a portion it of the capillary tube 34 and a second portion 83 in heattransfer relationship with the pressure conduit 25.

The electric motor 22 receives its power from lines 82 through the leads 83, one of which is connected in series with a conventional thermostatic switch 84. The switch 84 is opened and closed in response to pressure changes within a temperature sensitive bulb 86 mounted on the blind tube 88 extending upwardly from the storage vessel 34. The switch 86, with its associated temperature sensitive bulb 88, controls the motor 22 to maintain the temperature of the cooling unit 38 at a substantially constant value near 0' F. The function and operation of the blind tube 88 is more fully described and claimed. in the copending application of Graham S. McCloy,

means 38 is Serial No. 146,960, nowPatentNo. 2,645,094, July 4 14, 1953, filed March 1, 1950 and forms no part of the present invention.

A heater 90 is arranged in heat-exchange relationship with a portion of the liquid line adjacent the storage vessel 34 and is energized by a suitable switch mechanism indicated gendevice which is actuated through the plunger 96 each time the door I! is opened and closed. The switch mechanism 92 is so constructed as to energize the heater 9% when the refrigerator door ll has been opened and closed a predetermined number of times such as, for example, sixty times. Deenergization of the heater is effected in response to a predetermined high temperature of the evaporator or its outlet conduit. As shown, a thermal responsive member I04 is associated with the switch mechanism 92 and responds to the temperature of the evaporator.

The operation of the above described apparatus is, in many respects, similar to the system described and claimed in Patent No. 2,459,173 issued January 18, 1949 to the inventor of this invention and is as follows: During the refrigerating operation, liquid refrigerant conveyed from the condenser 28 by the liquid line 30 accumulates in the storage vessel 34 and spills over through the orifice 42 into the conduit means 35 through which it is conveyed to the evaporator '62 entering first the refrigerant passages 68 in the refrigerated shelf 65 and then flowing through the refrigerant passages 6- in the U-shaped portion of the evaporator 62. The liquid refrigerant evaporates at relatively low pressure in the passages 68 and 84 and the gaseous refrigerant is withdrawn through the suction conduit 14 by the motor-driven compressor 23 for compression and condensation in the condenser 28.

Because of some vaporization within the vessel 34 and the delivery of some flash gas to the vessel 34 by the capillary tube 32, a pressure drop across the orifice 42 is produced. This pressure drop is predetermined by the size of the orifice t2 and is effective to deliver the proper amount 7 of liquid refrigerant to the conduit means 36 for passage to the evaporator 62. Of course, this pressure drop will tend to force liquid upwardly in the elevated portion 40' of the conduit means but it is insufficient to force the liquid, in opposition to the head thereof, beyond the portion 40 into the heat exchanging portion 44. The effect is to bypass the heat exchanging portion 44 of the conduit means 36 and, consequently, this portion 44 of the conduit means 36 and the top 56 and back 48 of the cooling unit 38 secured thereto are not directly cooled by vaporizing refrigerant. However, the top 4-6 and back 48 of the cooling unit 38 are cooled suffi heater 9!] is energized 'by the closing of switch mechanism 92. Since the switch mechanism 92 is in series with motor switch 84, energization of the heater is effected only during'periods 5, of. operation of the motor and compressor. The heat supplied by theheater 90 vaporizes a major portion of the refrigerant liquid flowing through the line 30. The increased quantity of gaseous refrigerant conveyed to the vessel 34 increases the pressure drop across the orifice 42 to a value greater than the static head of therefrigerant liquid contained in the elevated portion 40 of the conduit means 36. As a result, liquid refrigere ant is forced out of the vessel 35 through the elevated portion 40 of the conduit means 36 to the heat exhanging portion 44 thereof, and thence to the evaporator 62. The liquid refrigerant thus forcedout of the vessel 34 floods the refrigerant passages 68 of the shelf and the refrigerant passages 64 ofthe evaporator 52 and overflows into the suction conduit 14.

i The hot refrigerant vapor in the pressure conduit 26 vaporizes refrigerant liquid in the portion ,80 of the suction conduit 14 and thereby raises the suction pressure in the conduit 14 and in the evaporator 62. The heater 90 continues to vaporize a major portion of the refrigerant liquid flowing through line 36; the vaporous refrigerant passing through the vessel 34 into the unrestricted end 39 of conduit means 35. The hot refrigerant vapor condenses in the heat exchanging portion 44 of the conduit means 36 and in the evaporator 62, transferring the latent heat, to these members for the melting of frost therefrom.

, Water formed by the melting of frost from the cooling unit 38 falls into a drip pan 98 positioned beneath the cooling unit 38 and is conducted, by means of a drain tube 100, to an evaporating tray H12 in the machinery compartment l4 where it is evaporated by heat from the condensing machinery. The defrosting operation is terminated by the switch mechanism 92 which deenergizes the heater 9!] in response to a redetermined high temperature of the cooling unit 38 as sensed by the thermo-sensitive bulb I 04.

The modification of the invention shown in Fig.5 is similar to the embodiment decribed and parts common to both embodiments are, indicated by similar reference characters. The only difference in these embodiments resides in the disposition and function of the heat exchanging portion of: the conduit means 36. As shown in Fig. 5, the heating exchanging portion of the conduit means 36 is indicated at Hi6 and is connected in, heat transfer relationship with the drip pan 98 in order to heat it to a temperature above freezing during a defrosting cycle. The

heat exchanging portion ills of Fig. is connected in the conduit means 35 and to the vessel 34 in exactly the same manner as the heat exchanging portion 44 of Fig. 1 and the refrigerating and defrosting operations of the two embodiments are similar.

From the foregoing description, it will be apparent that I have provided an improved refrigerating system having provisions for defrosting the evaporator thereof by the circulating of heated refrigerant through the evaporator and wherein parts of the refrigerator structure subject to frosting may be heated by the heated refrigerant during a. defrosting cycle and without directly subjecting such parts to liquified refrigerant during a refrigerating cycle.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

6 I What I claim is:

1. In refrigeration apparatus, the combination of an insulated cabinet structure enclosing a food storage chamber and including an evaporator disposed within said chamber for cooling media therein, a closed refrigerant circuit for conveying refrigerant to and from said evaporator, said circuit comprising a compressor, a suction conduit for conveying refrigerant from said evaporator to said compressor, a condenser for condensing refrigerant vapor compressed by said compressor, astorage vessel for selectively trapping or releasing refrigerant liquid, a liquid line including a restrictor for conveying refrigerant from said condenser to said vessel, first conduit means connecting a lower portion of said vessel with said evaporator, said first conduit means having a portion thereof elevated with respect to the liquid level in said vessel, second conduit means connecting an upper portion of said vessel with said evaporator, said second conduit means having a restriction therein, said restriction being ofasize sufiicient to pass all of the refrigerant flowing to said evaporator during the refrigerating operation of said circuit, and means for heating ,the refrigerant in said vessel to increase thevapor pressure in said vessel whereby refrigerant, liquid and vapor is forced from said vessel to said evaporator through said first conduit means to effect defrosting of said evaporator, said first conduit means having a portion thereof in heat exchange relationship with a portion of said cabinet structure cooled by said evaporator whereby the warm refrigerant flowing through said first conduit means defrosts that portion of said cabinet s ruc ture.

2. In refrigeration ap-paratusQthe combination of an insulated cabinet structure defining a food storage chamber and including an evaporator disposed Within said chamber for cooling the media therein, said evaporator cooling portions of said cabinet structure adjacent thereto below 32 F. whereby frost collects thereon, a closed refrigerant circuit for conveying refrigerant to and from said evaporator, said circuit comprising a compressor, a suction conduit for conveying refrigerant from said evaporator to said compressor, a condenser for condensing refrigerant vapor compressed by said compressor, a storage vessel for selectively trapping or releasing refrigerant liquid, a liquid line including a restrictor for con- Veying refrigerant from said condenser to said vessel, conduit means connecting a lower portion ofsaid vesel with said evaporator, said conduit means having a portion thereof elevated with re spect to the liquid level in said vessel, restrictor means including an orifice connecting an upper portion of said vessel with said conduit means at a point between said elevated portion and said evaporator, said restrictor means permitting refrigerant flowing from said vessel to said evaporator to bypass the elevated portion of said conduit means during the refrigerating operation of said circuit, said conduit means having a portion thereof between said elevated portion and said orifice in heat exchange relationship with said frost-collecting portions of said cabinet structure, and means for heating the refrigerant in said vessel to increase the vapor pressure in said vessel whereby refrigerant liquid and vapor is forced from said vessel through the elevated portion of said conduit means to said evaporator to effect defrosting of said evaporator and said frost-collecting portions of said cabinet structure.

3. In refrigerating apparatus, the combination 7. with a cooling unit defining a freezing :compartment and comprising a generally U -shaped, sheet metal evaporator structure having refrigerant passages formed therein said evaporator forming side and bottom walls ofsa'id cooling unit and a generally L-shaped sheet member forming the top and back walls of said cooling unit, of conduit secured in heat exchange relationship with portions of said L-shaped member, refrigerant circulating means including compressing and condensing apparatus for supplying liquid refrigerant at low pressure to therefrigerant passages of said evaporator alone to effect refrigeration of said Cooling unit and means for modifying the operation of said refrigerant circulating means to supply refrigerant at a higher pressure to both said conduit and said evaporator to effect defrosting of said cooling unit.

4. Refrigerating apparatus as claimed in claim 3, including means for heating the higher pressure refrigerant supplied to said conduit and said evaporator structure to effect defrosting of said cooling unit.

5. 'In refrigeration apparatus, the combination of an insulated cabinet structure defining a food storage chamber, a cooling unit disposed within said chamber and defining'a freezing compartment, said cooling unit comprising a generally U-shaped, sheet metal evaporator structure having refrigerant passages formed therein, said evaporator structure forming side and bottom walls of said unit, and a generally L-shaped sheet member forming the top and back wall of said cooling unit, a closed refrigerant circuit for conveying refrigerant to and from said evaporator, said circuit comprising a compressor, a suction conduit for conveying refrigerant from said evaporator to said compressor, a condenser for condensing refrigerant vapor compressed by said compressor, a storage vessel for selectively trapping or releasing refrigerant liquid, a liquid line including a restrictor for conveying refrigerant from said condenser to said vessel, conduit means connecting a lower portion of said vessel with said evaporator, said conduit means having a portion thereof elevated with respect to the liquid level in said vessel, restrictor means including an orifice connecting an upper portion of said vessel with said conduit means at a point between said elevated portion and said evaporator, said restricter means permitting refrigerant flowing from said vessel to said evaporator to bypass the elevated portion of said conduit means during the refrigerating operation of said circuit, said conduit means having a portion thereof between said elevated portion and said orifice in heat "exchange relationship with said L-shaped sheet member, and means for heating the refrigerant in said vessel to increase the vapor pressure in said vessel whereby the refrigerant liquid and vapor is forced from said vessel through the elevated portion of said conduit means to said evaporator to 'eifect'defrosting of said cooling unit.

6. In refrigeration apparatus, the combination of an insulated cabinet structure defining a .food storage chamber, an evaporator disposed within said chamber for cooling the media therein, a closed refrigerant circuit for conveying refrigerant to and from said evaporator, said circuit comprising a compressor, a suction conduit for conveying refrigerant from said evaporator to said compressor, a condenser for condensing refrigerant vapor compressed by said compressor, a storage vessel for selectively trapping or releasing refrigerant liquid, a liquid line including a restrictor for conveying refrigerant from said candenser to said vessel, conduit means connecting a lower portion of said vessel with said evaporator, said conduit means having a portion thereof elevated with respect to the liquid level in said vessel, restrictor means including an orifice connecting an upper portion of said vessel with said conduit means at a point between said elevated portion and said evaporator, said restrictor means permitting refrigerant flowing from said vessel to said evaporator to bypass the elevated portion of said conduit means during the refrigerating operation of said circuit, means for heating the refrigerant in said vessel to increase the vapor pressure in said vessel whereby refrigerant liquid and vapor is forced from said vessel through the elevated portion of said conduit means to said evaporator to effect defrosting of said evaporator, and a drip pan and drain positioned beneath said evaporator for catching and disposing of the water during the defrosting of said evaporator, said conduit means having a portion thereof between said elevated portion and said orifice arranged in heat exchange relationship with said drip pan whereby said drip pan is warmed when said evaporator is defrosted.

- Name 7 Date 7 2,513,823 Shreve July 4, 1950 2,598,408 McCloy May 2'7, 1952 

